It has to do with airflow in your nasal cavity. If your nose is plugged, you are unable to exhale through you nose and end words with a drum-like finish.

Here is the best example I can think of. When you drive a car and stop at a stop sign as you slow down and get closer to zero, you start to reduce the amount of brake pressure to slowly roll to a stop. If you kept constant brake pressure you would deceleerate at an increasing rate and stop too quickly.

That is similar to how you speak and end words, without your nasal cavity open, you lose this ability.

Anyway, if you've listened to any of this, it is all BS, I have no idea and this is a complete fabrication. Gad Damn am I good at Balderdash.